Dear All, (01)
An ontology for quantities and units needs to have a clear relationship with
an ontology that defines what is measured. We can decide to concentrate on
the former, but we need to do some work on the latter in order to define the
scope boundary. (02)
A requirement
-------------
An ontology for what is measured needs to encompass the following statements:
- The level of Lake Como in period 1990 to 2000 is cyclical with a period of
one year.
- The level of Lake Como in 1993 has a maximum value of 6 metres above chart
datum.
- The level of Lake Como on 23rd February 1993 is 5 metres above chart datum. (03)
This suggests that:
1) the_level_of_Lake_Como_in_period_1990_to_2000 needs to be recognised as
an object, because it has the classification "cyclical" and the property
"period";
2) level_of_Lake_Como_in_period_1993 is a similar type of object, and a part
(in some sense) of the object the_level_of_Lake_Como_in_period_1990_to_2000;
3) level_of_Lake_Como_in_period_1993 has values qualified as maximum,
minimum, mean, etc.;
3) level_of_Lake_Como_on_23rd_February_1993 is another part, which is
sufficiently short in the chosen engineering context to be regarded as an
instant and therefore have an unqualified value. (04)
A "practical engineering mathematics" approach
----------------------------------------------
With a practical engineering mathematics approach, there are no mysteries
here - height_of_lake_Como_about_chart_datum is a function with domain
Lake_Como and range Length. That Lake_Como is not a class does not worry a
"practical engineering mathematician" - it is a thing with mereotopology,
mereotopology is just another algebraic structure, and algebraic structures
are what most functions in mathematics have as their domain. Length is near
enough a manifold, which is another algebraic structure. (05)
If height_of_lake_Como_above_chart_datum_in_period_1990_to_2000 is a
subfunction defined by a constraint upon the domain. The
height_of_Lake_Como_above_chart_datum_on_23rd_February_1993 is the
evaluation the function at a point in its domain. (06)
Our task
--------
Perhaps this is to produce an ontology, or perhaps alternative ontologies,
each of which formalises what "practical engineering mathematicians" do. We
can then define which parts of these ontologies are within scope. (07)
Best regards,
David (08)
At 19:03 06/08/2009 -0400, you wrote:
>I wrote:
>> Q1 = a measurable aspect of a particular physical thing, e.g., the
>> height of the Eiffel Tower, the length of stick A, the weight of a
>> specific pack of cigarettes, as distinct from the weight of the next
>> pack of cigarettes in the same carton. (Q1 = 'particular quantity', a
>> subtype of 'property instance' = trope)
>>
>>
>I should make clear that I agree with Pat that this concept is probably
>not useful in the ontology. It just has to be in the list of terms and
>definitions so that we don't confuse it with any useful concept, and
>don't get accused of ignoring it. We want to make and document the
>decision to include it or exclude it.
>
>And I aver that it is definitely an important concept to the VIM, but
>that is because much of the VIM is about making measurements of the
>'tropes' -- measuring individuals and characterizing the individual results.
>
>-Ed
>
>--
>Edward J. Barkmeyer Email: edbark@xxxxxxxx
>National Institute of Standards & Technology
>Manufacturing Systems Integration Division
>100 Bureau Drive, Stop 8263 Tel: +1 301-975-3528
>Gaithersburg, MD 20899-8263 FAX: +1 301-975-4694
>
>"The opinions expressed above do not reflect consensus of NIST,
> and have not been reviewed by any Government authority." (09)
============================================================
David Leal
CAESAR Systems Limited
registered office: 29 Somertrees Avenue, Lee, London SE12 0BS
registered in England no. 2422371
tel: +44 (0)20 8857 1095
mob: +44 (0)77 0702 6926
e-mail: david.leal@xxxxxxxxxxxxxxxxxxx
web site: http://www.caesarsystems.co.uk
============================================================ (010)
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